[FEAT] Add PR review time trend chart — track code review velocity over time

[Priyanshu-byte-coder]

Problem Statement

The PRs widget shows average merge time as a single number. This hides whether review velocity is improving or degrading over time — an important signal for team productivity.

Proposed Solution

• New mini line chart in the PRs card showing avg merge time per week for the last 12 weeks
• Data from GitHub /search/issues or /pulls API, grouped by merged_at week
• Trend line with color coding: green (improving), red (degrading)

Alternatives Considered

• Bar chart per month: Less granular, trends harder to see
• Table view: Less visual impact

Acceptance Criteria

• Line chart showing weekly avg merge time (hours or days) for last 12 weeks
• Trend direction badge (improving / degrading / stable)
• Tooltip showing exact avg for each week
• Graceful empty state if user has <5 merged PRs

Additional Context

GitHub API: GET /search/issues?q=is:pr+author:<login>+is:merged&sort=updated&per_page=100
Then group by pull_request.merged_at week and compute avg (merged_at - created_at).

[mallya-m]

Hi @Priyanshu-byte-coder!
I would like to work on this issue under GSSoC 2026

I have 5 merged PRs here (#303, #411, #586, #602, #306) and this is a natural extension of my PR #586 work on PR review metrics.

I already know the /search/issues PR data structure from that PR. Will group merged PRs by merged_at week, compute avg (merged_at - created_at) per week, and render a Recharts LineChart — already in the project. Trend badge (improving/degrading/stable) based on last 2 weeks vs previous 2 weeks comparison.

/assign
Can you assign this to me? github.com/mallya-m

[tmdeveloper007]

Proposed Implementation Plan

Here is a detailed, technically solid, step-by-step approach to solve this issue:

1. Create /api/metrics/pr-trends and fetch the user's merged PRs from GitHub (GET /search/issues?q=is:pr+author:<login>+is:merged).
2. Calculate the merge duration (merged_at minus created_at in hours) and group them by week for the last 12 weeks to compute average weekly review times.
3. Render a gorgeous line chart widget using Recharts to present this trend, accompanied by a dynamic trend badge ('Improving' in green if review speeds up, 'Degrading' in red otherwise) and custom tooltips.

I would love to work on this issue and implement the proposed solution. Could you please assign this issue to me? Thank you!

[VIDYANKSHINI]

I would like to work on this issue under GSSoC 2026.

I am interested in implementing the PR review time trend visualization to provide better insights into code review velocity and contribution productivity over time. The feature would make the PR analytics section more informative by showing whether merge efficiency is improving or slowing down across recent weeks.

Planned scope:

• Add a mini line chart inside the PRs analytics card

• Fetch merged PR data using the GitHub API

• Group PRs by merged week for the last 12 weeks

• Calculate average merge/review time using:

  • merged_at - created_at

• Add trend direction indicator:

  • Improving
  • Degrading
  • Stable

• Add tooltip support showing exact weekly averages

• Handle empty/low-data scenarios gracefully for users with limited merged PR history

• Ensure responsive and clean chart rendering

• Keep the implementation focused without unrelated UI changes

Please assign this issue to me if it is still available.

[github-actions]

Assigned to @VIDYANKSHINI! You have 7 days to open a PR. No PR after 7 days = auto-unassigned so others can pick it up. Good luck!